With advances in semiconductor technology, increasingly smaller and more efficient image sensors and cameras become possible. For this reason, an increasing number of endoscopes have an image sensor at the distal end (“chip-on-the-tip”). Yet, there continue to be numerous applications in which, for various reasons, an image generated by an objective is intended to be first transmitted from the distal end to the proximal end of an endoscope by way of a relay lens system. At the proximal end of the endoscope, the transmitted image can be observed directly through an eyepiece or can be captured by a camera. For this reason, relay lens systems are likewise subject to constant improvement and further development so as to improve the imaging properties and/or to lower the production costs.
GB 1 534 541 describes a relay lens system, in which each inversion is corrected with respect to chromatic aberration.
In U.S. Pat. No. 5,097,359 describes a configuration of a relay lens for an endoscope.
U.S. Pat. No. 5,142,410 describes relay lens systems, in which individual inversions are corrected.
U.S. Pat. No. 5,933,275 describes a relay lens system composed of a plurality of relay lens units. With respect to the longitudinal chromatic aberration, at least one relay lens unit A is undercorrected, and at least one relay lens unit B is overcorrected such that the undercorrected longitudinal chromatic aberration and the overcorrected longitudinal chromatic aberration cancel each other out (column 2, line 65 to column 3, line 7).
It is an object of the present invention to provide an improved relay lens system and an improved endoscope.